Recently, energy-related problems have become a big issue in international society. Among the problems are air pollution and fossil energy deficiency. In order to overcome these problems, the development of a substitute energy is desperately needed.
The hydroelectric power method has been used as an important method for generating electric power. However, a hydroelectric power plant requires that a very large area of land be flooded, thus reducing the land available for other purposes and damaging natural life systems on the land.
Another substitute energy which is being developed in the industry is nuclear energy. This energy causes some problems such as a nuclear waste disposal, radioactive substances, and other concerns which have become international issues. In addition, in some countries, it is very difficult to prepare an area in which the radioactive waste and substance can be treated, due to unstable processing methods for these materials.
In order to overcome the above-described problems, a technique for using solar energy, which is known as a non-polluting, substitute energy, has been intensely studied. The technique has some problems in that solar energy is more effectively obtained outside the atmospheric orbit; thus, solar energy is more effectively used in a space station or a satellite. However, within the earth's atmospheric orbit, since the amount of solar energy varies in accordance with the weather conditions, solar energy's use for home heating systems is limited.
In addition, a tidal power plant method has been developed, which is directed to using the ebb and flow difference of the tide. However, this method is limited in application to specific places where a predetermined amount of ebb and flow difference of the tide can be obtained.
Another technique, basically directed to using the force of water waves, has been developed as a water wave force-based electric power generating apparatus and a method for creating such. In connection with this technique, there are Korean Patent No. 35,913 (corresponding to U.S. Pat. No. 5,066,867) and Korean Patent No. 96-11790, which improves upon Korean Patent No. 35,913.
This water wave-based electric power generating apparatus is directed to converting the force generated as buoys move up and down on the waves into a rotational force, which is used for driving an electric power generator. Since at least 1 m waves are always generated in the sea, it is possible to build a power plant to generate the desired electric power using this water wave-based electric power generating apparatus. In addition, this power plant is installed in the sea which occupies 78% of the earth's surface providing almost unlimited area for installing the power plant containing the water wave-based electric power generating apparatus.
Another technique for overcoming the above-described problems is a wind power generator. However, the wind power generator requires a steady, strong wind. Therefore, there is a problem in consistently obtaining the necessary wind.
In the conventional wind power generator, a plurality of propellers are fixed at predetermined angles, respectively, for effectively receiving the wind. Therefore, it is impossible to use the wind to generate power when the wind velocity is below a predetermined level, for example, 20 m per second. Conversely, if the wind velocity exceeds 60 m per second, the high force of the wind may break the propellers.